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I'm in the middle of rebuilding my new 10 bolt rear end. Current backlash is between 4-5 "2 cut gears", pinion depth shim 0.32 right at 19 inch/lbs of pre load, but am a little bit confused with my pattern, I was expecting it a little bit more centered on the drive side. This is my first time playing with gears so any help and tips would be appreciated!
You dont need preload on the pinion to run a pattern just so you know, there just needs to be zero slack but does not have to be set to a specific amount, just so you can turn it. Are you holding the ring gear tight and you turn the pinion to get the pattern? Also, can you open the backlash up to 7 or 8 and run the pattern again? Its close though....
You dont need preload on the pinion to run a pattern just so you know, there just needs to be zero slack but does not have to be set to a specific amount, just so you can turn it. Are you holding the ring gear tight and you turn the pinion to get the pattern? Also, can you open the backlash up to 7 or 8 and run the pattern again? Its close though....
I thought 2 cut gears are suppose to run at 3-6 thousands of an inch. I did however go with a 0.03 pinion shim increase, this is what I got with 0.35 depth. Oh and I am using a wrench to turn the ring gear while holding the pinion yoke.
Erick , I would add .002 more to the .035 shim . I see the coast side a little close to the toe , and the drive side closer to the heal . The .002 will move them both closer to the center of each other . I would set the back lash at .006 to .007 and see what happens . Let us know .
I also like to put some prelead on the pinion at around 20in lbs . This way I know the bearing are seated and I can duplicate the pattern when assembled . I too use the ring gear bolt to rotate back and forth . The reverse rotation puts enough force to give a good pattern trying to drive the pinion along with the preload . Also about 3 passes is enough . To many and you can skew the reading .
6 to 7 backlash on 2 cut gears? That is what confuses me if you could enlighten me please.
I think you are right about needing a lower backlash on 2 cut gears. The motives I installed called for 7-9 backlash, but I remember reading gm oe replacement brand, i forget the name, requiring 3-5 and i believe they are 2 cut gears.
Read your gear install instructions and find out what backlash they require. Different manufactures have different figures
The aam gears say in the sheet is at about .004 . These are the oem gears GM uses .Talking with the engineers at aam ( Kevin ) says that's not a given . It could be your gear set may be in that spec . Not all gears sets set up the same . Some require more back lash the get both sides centered if the pattern where it needs to be . I have set up the aam gears as much as .008 . some at .007 but usually between .005 and .007 to center the pattern . I went as far as sending aam engineers some pictures and agreed the .008 was acceptable with the pattern I had . All gear sets are a little different even the same brand .
Reason I suggested .006 to .007 because adding .002 more shim it would push the pinion deeper in the ring gear . Hoping the 2 sides would move closer together ( heel to toe ) . The wider backlash would bring the pattern back to the top some and compensate for the thicker shim . Its possible you may need .004 to .005 .
Just don't know what it will do until you try a few patterns .
Here is summary of where am sitting at the moment; at 0.032 depth the pattern is close, I just tried 0.037 and 0.038 and it doesn't look right to me,maybe I'm missing something. Then I tried 0.034 and I think that's as close as I've been to a good pattern at least to me, I hope you guys can lead me in the right direction. I appreciate your help.
0.034 Depth
0.034 Depth
0.037
0.037
I'm using US standard gears calls for 3-6 in the manual for 2 cuts.
04-11-2017, 11:45 PM
First timer, GM 10 bolt rebuild pattern advice 
